A wide variety of devices, including personal digital assistants, cellular telephones, and appliances now incorporate sophisticated processors, monitors or displays, and other elements once found only in expensive computers. Incorporation of processors has enabled cellular telephones to do more than just serve as a telephone—it is now common for such cell phones to include phone directories, digital cameras, music playback, video games, and to offer a high degree of programmability or customization to the cell phone end user or service provider. Similarly, personal digital assistants, or PDAs, commonly include software including calendar, e-mail, word processing, and other traditional computer functions.
But, while traditional computers are usually plugged in to a wall socket or outlet that provides electric power on a continuous basis, many portable devices such as cell phones and PDAs are powered by rechargeable batteries incorporated into the electronic computerized device. This limits the amount of time one can use such a portable device to the amount of time the rechargeable battery can provide adequate power to operate the device. One could simply use bigger batteries in situations where long-lasting operation was desirable, but battery size and performance is often traded off for smaller overall device size, lighter weight, and lower cost.
Engineers have addressed this issue by developing electronic devices that require less power to operate, or that can operate at reduced speed to conserve power. Such methods are also sometimes employed in other systems such as normal desktop computers and laptop computers, particularly where significant power savings can be realized. Reduced power consumption in desktop computers results in a reduction in utility bills, energy demand, and pollution, and is particularly desirable when it can be implemented across a wide number of systems without a significant reduction in performance.
It is therefore desirable that computerized devices have power management capability such that power can be conserved.